Release notes are version independent, so remove version/release
values. We've found that projects now require the service package
to be installed in order to build release notes, and this is entirely
due to the current convention of pulling in the version information.

Release notes should not need installation in order to build, so this
unnecessary version setting needs to be removed.

The positional decorator results in poorly maintainable code in
a misguided effort to emulate python3's key-word-arg only notation
and functionality. This patch removes keystoneclient's dependance
on the positional decorator.